1. Field of the Invention
The present invention relates to a magnetic head, a magnetic read/write apparatus and a method for manufacturing the magnetic head.
2. Discussion of Background
In a rotary actuator-type magnetic read/write apparatus, the technology that reduces the dependency of the magnetic head on the skew angle in order to ensure that the flying height is constant from the internal circumference of the magnetic disk to the external circumference, and to ensure a stable flight attitude, is of extreme importance. This technology improves reliability for high density recording, which requires that spacing loss be minimized by reducing the flying height. Consequently at very small flying heights, even if the flying height of the magnetic head changes only very slightly during a read or write operation, the magnetic head is likely to come into contact with the magnetic disk, causing a head crash, which in turn, causes problems such as destruction of data on the magnetic disk.
The technology to ensure that the flying height is constant from the internal circumference of the magnetic disk to the external circumference, and to ensure a stable flight attitude, is also essential for the zone bit recording technology required by high capacity magnetic disk drives. The zone bit recording technology is disclosed, for instance, in Japanese Unexamined Patent Publication (Kokai) No. 30328/1992, U.S. Pat. No. 4,894,734 and U.S. Pat. No. 5,087,992.
As a means for responding to the requirements described above, various types of magnetic heads, each of which features air bearing surfaces with a specific and unique contour, have been disclosed. White, for instance, discloses TPC (Transverse Pressurization Contour) type sliders in U.S. Pat. No. 4,673,996 and U.S. Pat. No. 4,870,519. A TPC slider is provided with very small indented portions running the entire length of the rail portion along the sides. A TPC slider, when fitted in a rotary actuator-type magnetic read/write apparatus, generates dynamic lift pressure at the indented portion due to the air current which flows in from the transverse direction when the skew angle is large, to prevent any reduction of the flying height at positions where the skew angle is large. With this, a consistent flying height is ensured from the internal circumference to the external circumference of the magnetic disk and, at the same time, the flight attitude is stabilized.
Also, Japanese Unexamined Patent Publication (Kokai) No. 101781/1985 discloses a slider for a magnetic head with a reduced dependency on the skew angle, achieved by making the rail width of the slider rail at the center in the direction of the length smaller than the width at both ends.
Furthermore, U.S. Pat. No. 5,062,017 discloses a magnetic head in which air bearing surfaces provided with an inside edge and an outside edge are formed on the surfaces of the rail portions. The inside edge and the outside edge are made to converge from the leading end edge of the slider toward an inflection point, and are made to diverge from the inflection point to the trailing end edge of the slider, thereby inhibiting any change in the flying characteristics relative to the skew angle.
Moreover, Japanese Unexamined Patent Publication (Kokai) No. 246067/1990 discloses a slider for a magnetic disk apparatus, which is formed in such a manner that the rail width is reduced starting from the end where the air flows in toward the end where the air flows out.
Of the technologies in the known art described above, in the TPC slider disclosed by White, the desired contour of the air bearing surfaces is imparted by machining over the entire length of the rail portions. The contour formation in this case must be performed through fine machining such as dry etching technology, including ion milling. Because of this, in the prior art technology, which requires machining over the entire length of the rail portion, the openings of the mask, which is necessary for dry etching, must be longer than the entire length of the rail portion and, inevitably, minute particles from the slider, generated in the dry etching process, adhere to the two side surfaces of the slider. The strength of adhesion of these particles to the slider is not great, and when the magnetic head is being operated in a magnetic read/write apparatus, the particles adhering to the side surfaces of the magnetic head enter into the narrow spacing gap between the magnetic disk and the magnetic head. This may damage the magnetic disk irreparably.
In addition, at one end of the slider in the direction of the length, bond pads (bump) for the magnetic transducers are provided. The bond pads, unlike the slider, which is constituted of a hard ceramic structure, are constituted of a soft metal material, such as gold. This causes the bond pads to be dry etched excessively in comparison with the slider and it may result in the surfaces of the bond pads falling off the surface of the slider. This, in turn, makes connecting lead wires to the bond pads difficult. The magnetic head disclosed in U.S. Pat. No. 5,062,017 requires a specifically contoured air bearing surfaces, in which the inside edge and the outside edge are made to converge from the leading end edge of the slider to an inflection point, and to diverge from the inflection point toward the trailing end edge of the slider.